Spark-plug



F. L. DYER.

SPARK PLUG.

APPLICATION FILED JAN.25. ma.

Patented May 20, 1919.

FRANK I. DYER, 0F MONTCLAIR, NEW JERSEY.

SPARK-PLUG.

I Specification of Letters Patent.

Patented May 20, 1919.

Application filed January 25, 1918. Serial No. 213.670.

To all whom it may concern:

Be it known that I, FRANK L. DYER, a citizen of the United States, andresiding at Montclair, in the county of Essex and State of New Jersey,(post-oflice address No. 55 Liberty street, New York city,) haveinvented certain new and useful Improvements in Spark-Plugs, of whichthe following is a full, clear, and exact description.

My invention relates to various new and useful improvements in sparkplugs of the general type described in my application for Letters Patentfiled April 27, 1917, and numbered serially 164,849. In my saidapplication I show a spark plug in which the central electrode is firmlyand securely locked within the porcelain or other refractory insulator,preferably by a process analogous to electric butt-welding. Inconstructing such plug, I propose taking two lengths of metal of therequired diameter, and preferably reduced in cross section at theirabutting ends, or what amounts to the same thing, a single length ofmetal having an intermediate portion cut awayto secure the correspondingreduction in cross section, and passing through the metal, or metals, aheating current of low voltage and very high amperage so as to heat thesame at-the locality of small cross section and make the metal plastic,or even molten, after which pressure is applied lengthwise to cause theplastic or molten metal to form a tight anchoring seal with theporcelain, and also, in the case where two metal lengths are used, tocause the abutting ends thereof to be electrically welded. Theadvantages of such a spark plug are the ease and economy with which itcan be made, and the fact that the central electrode is anchored to theporcelain in situ, and each is free to expand or contract under chan esin temperature, notwithstanding difl erences in coefiicients ofexpansion, thus doing away with a potent source of diflicultyencountered when the central electrode throughout its length is cementedwithin the porcelain.

The ob]ect of my present invention is to effect a further economy inconstruction,

which "I accomplish by making the section of the central electrode,which is exposed to the sparking effects, of nickel, and by making therest of the central electrodes of steel or other cheaper metal, the twosections being electrically welded together as I explained in saidapplication.

Another object of my invention is to improve the tightness of the jointbetween the central electrode and the porcelain, which I do by makingthe joint of an alloy having nearly the same coefficient of expansion asporcelain. An alloy of nickel and steel, where the percentage 9f nickelis properly selected, has this property, and therefore when a nickel andsteel section are welded together it is possible to so adjust conditionsof cross section, current used, etc., as to secure at the weldpractically an alloy having the desired coefficient of expansion. Orinstead, the entire length comprising the central electrode can be madeof the desired all0ysuch as nickel-steel, with a reduced intermediatesection to be made plastic or molten by the current to effect therequired seal. Or instead, between two sections of nickel and steel maybe placed an intermediate section of the desired alloy, of smaller Fig.2, a plan view of the clamp for the upper section of the centralelectrode;

Flg. 3 a cross section on the line 33 of- Fig. 1; g I

Fig. 4 a section showing the joint after being formed and constituting atight seal with the porcelain;

Fig. 5 a longitudinal section on a larger scale showing the two metalsections with difierently reduced ends;

Fig. 6 a corresponding view of a slightv modification; v

Fig. 7 a corresponding view showing the Fig. 9 a longitudinal sectionalView showing the central electrode as being formed of a single length ofthe desired alloy, and hav ing a reduced section where the heating is tobe localized.

In the above views, corresponding parts are represented by the samenumerals.

The porcelain 1, is shown as supported by the two arms 2, 2, from a base3 from which extends the section 4 of the central electrode, saidsection being of nickel or other suitable metal for the purpose. Theother sect-ion 5, made of steel, is carried by a split clamp 6 (see Fig.2) to which the desired pressure may be applied.

The heating current is supplied by any ,suitable transformer 7, being oflow voltagesay from 3 to 6 volts and of the desired .high amperage. InFig. 1, the abutting ends of the sections 4 and 5 are shown ascorrespondingly reduced. When the heating current is applied, thereduced ends become intensely heated to plasticity or even to a molten.state, and by applying pressure lengthwise, the metal is squeezed outforming a tight seal asshown in Fig. 4, and simultaneously welding thetwo sections together. If desired, the heating may be continued untileither or both sections 4 and 5 is made plastic for a considerable partof its length, so that when longitudinal pressure is applied the metalwill be forced radially outward so as to bring a considerable length ofthe central electrode in intimate contact with the porcelain and thusclose the slight air space between the central electrode and theporcelain to permit more effective radiation of heat from the centralelectrode. This feature is especially important when the centralelectrode is composed wholly or largely of a nickel steel alloy ofnearly the same coefficient of expansion as the porcelain, because inthat case the central electrode for its whole length, if necessary, canbe squeezed in contact with the porcelain without danger from unequalexpansion and contraction.

According to Kent, The Mechanical Enginecrs Pocket-Book, John Wiley &Sons, Inc., New York, 1916, page 499, an alloy of nickel and steel inWhich the percentage of nickel varies between 28.7 and 34.4% has acoeflicient of expansion of from .00001041 to .00000458 for each degreeC., and it can be assumed that most spark plug porcelains.

have a coefficient of expansion in this neighborhood and between theseextremes. Therefore, by properly selectin the percentage of nickelin thealloy, a coe cient of expansion can be secured to nearly correspond withthat of the porcelain used. Preferably the coeflicient of expansion ofthe alloy should, if anything, be very slightly less than that of theporcelain, rather than greater, for the the latter shrink away from theporcelain and possibly make the joint leak. The properproportioning ofthe two metals constituting the alloy may be afi'ected by varying thecross-sectional areas of the abutting ends as shown in Figs. 5 and 6,and suitably controlling the current and other factors. Or instead, aseparate section 8 of the desired alloy may be inserted between thesections 4 and 5, .and being suitably reduced in area (for example, asshown in Fig. 8), will affect the localization of the current so as tobecome plastic or molten, and form the seal when longitudinal pressureis applied, at the same time welding the sections 4 and 5 together.Instead of using two sections 4 and 5 and welding them together, asingle length 9 may be used, made of-the desired alloy, .and reduced atan intermediate part, asv shown in Fig. 9, to thus localize the currentand permit the metal to be squeezed outward to form the anchoring sealwhen longitudinal set forth.

2. In a spark plug, an integral or onepiece porcelain or other refractory insulator therefor and a composite central electrode therein,comprising a nickel section located in the bore of the insulatortandwhich is to be subjected to the effect of sparking, and a steel sectionwelded thereto and also located in the bore of the insulator, the jointbetween the sections being located in the bore of the insulator,substantially as set forth.

3. In a spark plug, an integral or onepiece porcelain or otherrefractory insulator therefor and a composite central electrode therein,comprising a nickel section located in the bore of the insulator andwhich is to be subjected to the effect of sparking, and a steel sectionwelded thereto and also located in the bore of the insulator,

the joint between the sections bein located in the bore of the insulatorand eing expanded to tightly anchor the composite central electrodeinplace, substantially as set forth.

4. In a spark plug, a porcelain or other refractory insulator therefor,and a central electrode therein, anchored to the bore thereof by a tightexpanded joint of a metal alloy Whose coefiilcient of expansionapproximates that of the insulator, substantially as set forth.

5. In a spark plug, a porcelain or other refractory insulator therefor,and a central electrode therein, anchored to the bore thereof by a tightexpanded metal joint of a metal alloy Whose coefficient of expansion isslightly less than that of the insulator, substantially as set forth.

'6. In a spark plug, a porcelain or other refractory insulator therefor,and a central electrode therein, anchored to the bore thereof by a tightexpanded joint of a nickel-steel alloy whose coeflicient of expansionapproximates that of the insulator, substantially as set forth. 7

7.. In a spark plug, a porcelain or other refractory insulator therefor,and a central electrode therein made of a nickel and a cient ofexpansion approximates that ofthe insulator, substantially as set forth.

8. In a spark plug, an integral or onepieee porcelain or otherrefractory insulator therefor and a composite central electrode therein,comprising a nickel section located in the bore of the insulator andwhich is to be subjected to the effect of sparking, and a steel sectionWelded thereto and also located in the bore of the insulator, the jointbetween the sections being located in the bore of the insulator andbeing expanded into intimate contact there with on both sides of thejoint to tightly anchor the composite central electrode in place,substantially as set forth.

This specification signed and witnessed this 24th day of January, 1918.

FRANK L. DYER.

Witnesses:

A. E. BENTON, ABRAHAM FASTONE.

